The nitrogen fixation potential of arctic cryptogram species is influenced by enhanced UV-B radiation

Abstract. Effects of enhanced UV-B (representing a 15% ozone depletion) on cyanobacterial nitrogen fixation were measured at a high arctic site (Adventdalen, 79°N, Svalbard) and a subarctic site (Abisko, 68°N, Sweden). Nitrogen fixation potential (acetylene reduction) by cyanobacteria associated with the moss Sanionia uncinata in vegetation exposed to experimentally enhanced levels of UV-B for 3 and 4 years in the high arctic in Adventdalen was reduced by 50% compared to controls after 3 years. No reduction in nitrogen fixation potential was observed in cyanobacteria associated with the moss Hylocomium splendens when previously exposed to enhanced UV-B in Abisko for a 7-year period. However, in the same experiment a 50% increase in summer precipitation stimulated nitrogen fixation potential by up to 6-fold above the natural precipitation treatments both in cyanobacteria associated with vegetation exposed to natural and enhanced UV-B radiation. In contrast to the lack of UV effect on moss-associated nitrogen fixation at the subarctic site, nitrogen fixation potential by the dominant lichen species Peltigera aphthosa was reduced by 50% when measured after 8 years exposure to elevated UV-B treatment. Evidence from these studies highlights the importance of UV-B radiation for cyanobacterial nitrogen fixation in the Arctic and future impact on nitrogen availability in such plant communities.

Johanson, Ulf (författare)
Callaghan, Terry V. (författare)
Lee, John A. (författare)
Gwynn-Jones, Dylan (författare)
Björn, Lars OlofLund University,Lunds universitet,Molekylär cellbiologi,Biologiska institutionen,Naturvetenskapliga fakulteten,Molecular Cell Biology,Department of Biology,Faculty of Science(Swepub:lu)fysb-lob (författare)
Molekylär cellbiologiBiologiska institutionen (creator_code:org_t)

Ingår i:Oecologia: Springer Science and Business Media LLC133:1, s. 90-931432-19390029-8549

Av författaren/redakt...: Solheim, Bjørn; Johanson, Ulf; Callaghan, Terry ...; Lee, John A.; Gwynn-Jones, Dyl ...; Björn, Lars Olof

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